Researchers from Stockholm University have published a new assessment in the journal Environmental Science & Technology on per- and polyfluoroalkyl substances (PFAS), man-made hazardous chemicals that are spread globally in the atmosphere and are distributed through rainfall and snow, even in remote locations.
The researchers argue that the global spread and persistence of the chemicals, coupled with their risk to health, represents a new planetary boundary, and that the global spread of four assessed chemicals shows the planetary boundary for chemical pollution as being exceeded.
The researchers note that guideline values for PFAS in drinking water, surface water and soils have decreased dramatically, reflecting the greater understanding of the potential effects of the chemicals. At the same time, levels of some harmful PFAS in the atmosphere have not notably declined, despite them being phased out by the main manufacturer, 3M, some two decades ago. This is because PFAS continually cycle back into the atmosphere from the planet surface, for example by transportation of seawater to marine air by aerosols from sea spray.
In their paper, ‘Outside the Safe Operating Space of a New Planetary Boundary for Per- and Polyfluoroalkyl Substances (PFAS)’, the researchers conclude, for example, that levels of PFOA and PFOS in rainwater often greatly exceed US Environmental Protection Agency (EPA) Lifetime Drinking Water Health Advisory levels.
Lead author Professor Ian Cousins, of the Department of Environmental Science, Stockholm University, is quoted in reports as stating: “Based on the latest US guidelines for PFOA in drinking water, rainwater everywhere would be judged unsafe to drink. Although in the industrial world we don’t often drink rainwater, many people around the world expect it to be safe to drink and it supplies many of our drinking water sources.”